Java - Firma electronica xml con Xades-EPES

public class Main {

    private static final String CERT_FOLDER = "/home/jperez/Documentos/factura_electronica";

    private static final String CERT        = "cert.pm";

    private static final String KEY_STORE   = "KeyStore";

    private static final String PASS        = "summan"; //the same in cert and keystorage

    private static final String TSA_URL     = "http://XXX.XXX.XXX/ts.inx";

    private static final String TSA_USER    = "XXXXXXXX";

    private static final String TSA_PASS    = "XXXXXXXX";

    private static final String UNSIGNED    = "/home/jperez/Documentos/factura_electronica/unsigned.xml";

    private static final String SIGNED      = "/home/jperez/Documentos/factura_electronica/signed-epes.xml";

    private static final String SIGNEDT     = "/home/jperez/Documentos/factura_electronica/signed-t-epess.xml";

    private static final String VERIFY      = "/home/jperez/Documentos/factura_electronica/verify-epess.txt";

    private static final String VERIFYT     = "/home/jperez/Documentos/factura_electronica/verify-t-epes.txt";

    private static final String DOCUMENT    = "/home/jperez/Documentos/valid0.xml";

    private static final String DOCSIGNED   = "/home/jperez/Documentos/factura_electronica/signed.epes.xml";

    public static void main(String[] args) throws Exception {

        System.out.println("______________________");

        System.out.println("\tSign");

        System.out.println("______________________");

        signBes();

        System.out.println("______________________");

        System.out.println("\tVerify");

        System.out.println("______________________");

        verifyBes();

    }

    private static void signBes() throws Exception {

        Document doc = DocumentBuilderFactory

                .newInstance()

                .newDocumentBuilder()

                .parse(new File(DOCUMENT));

        Element elem = doc.getDocumentElement();

        DOMHelper.useIdAsXmlId(elem);

        KeyingDataProvider kdp = new FileSystemKeyStoreKeyingDataProvider(

                "JKS",

                CERT_FOLDER + CERT,

                new FirstCertificateSelector(),

                new DirectPasswordProvider(PASS),

                new DirectPasswordProvider(PASS),

                true);

        DataObjectDesc obj = new DataObjectReference("#" + elem.getAttribute("Id"))

                .withTransform(new EnvelopedSignatureTransform());

        SignedDataObjects dataObjs = new SignedDataObjects().withSignedDataObject(obj);

        XadesSigner signer = new XadesBesSigningProfile(kdp).newSigner();

        signer.sign(dataObjs, elem);

        TransformerFactory tFactory = TransformerFactory.newInstance();

        Transformer transformer = tFactory.newTransformer();

        DOMSource source = new DOMSource(doc);

        StreamResult result = new StreamResult(new File(SIGNED));

        transformer.transform(source, result);

    }